Monday, 1 February 2021

REPAIRING / SERVICING TV SAMSUNG UE55RU7120

Technical description and composition of the SAMSUNG UE55RU7120 TV, panel type and modules used. The composition of the modules.

SAMSUNG LED
Model: UE55RU7120 UE55RU7120U

Chassis / Version: FA04

Panel: CY-NN055HGLV2H

LED backlight: AOT_55_NU7100_2X40_3030C

T-CON: PFC (so-8), PWM (so-16)

LED driver (backlight): integrated into PSU

PWM LED driver: SO-16 Step-Down

MOSFET LED driver: TO-252

Power Supply (PSU): BN44-00932Q L55E7_RHS

PWM Power: PFC SO-8, PWM SO-16

MOSFET Power: TO-252, TO-220F

MainBoard: BN41-02703A BN94-14197L

IC MainBoard: CPU, eMMC, DRAM, AUDIO, DC / DC

Tuner: BN40-00331B

Specifications UE55RU7120U
SAMSUNG UE55RU7120
General recommendations for TV LCD LED repair
Possible malfunctions

- TV SAMSUNG UE55RU7120 does not turn on and does not show any signs of turning on, does not respond to control buttons and to the remote control.

In some of these cases, the main switching power supply, the BN44-00932Q module, is faulty. It is necessary to measure the output voltages in its secondary circuits, and if they are completely absent, the serviceability of the power switches (TO-252, TO-220F) and rectifying diodes should be checked for a possible breakdown (short circuit).
In case of breakdowns in the secondary circuits, the converter, as a rule, can operate in an emergency in the short-circuit mode, and in the event of a short circuit in the power elements of the primary circuit, the mains fuse usually breaks off.
Breakdown of Mos-Fet switches used in switching power supplies is often caused by malfunctions of other elements, for example, in the power supply circuit of a PWM controller, in frequency setting or damper circuits, as well as in negative feedback stabilization. PWM microcircuits (PWM) PFC SO-8, PWM SO-16 are usually checked by replacing them with new ones, or knowingly working.

- There is no picture, but there is sound and all other functions work. Sometimes when you turn it on, the image appears and disappears for a second.

Usually, in such cases, there is no backlighting of the LED panel (matrix). The reason may be in the breakage of the backlight LEDs, in the stabilization of their power supply, or in the violation of the contact connections of the AOT_55_NU7100_2X40_3030C strings connectors.
To identify an open circuit in the LED lines without disassembling the panel, a current source is required. It is impossible to open the junctions connected in series with a simple multimeter; a voltage of several tens of volts is required.

- The TV does not go into operation, does not respond to the remote control. The indicator on the front panel is on or blinking.

Repair or diagnostics of the BN41-02703A motherboard should begin with checking the stabilizers and power converters necessary to power the microcircuits and matrix. If necessary, you should update or replace the software (software). In cases of attempts to repair the MB (SSB) board, it is necessary to check the serviceability of its elements - CPU, eMMC, DRAM, AUDIO, DC / DC which may need to be replaced with new ones. If a BGA processor is installed, there is a possibility of a violation of the soldering of the contacts of its pins with the board (detected by warming up).

Before changing the tuner BN40-00331B, if it is not possible to tune to television channels, you should make sure that there are supply voltages, which must be measured at the corresponding terminals of the tuner and check the software for correctness. The pulses of data exchange between the tuner and the processor can be monitored with an oscilloscope

Once again, I remind TV users: do not try to repair yourself without the appropriate knowledge, experience and the necessary qualifications! Trust the repair to professionals with sufficient experience in the field of electronic repair.

Additional MainBoard Repair

The appearance of the MainBoard BN41-02703A is shown in the figure below:







BN41-02703A

External view of the power supply

Main features of the SAMSUNG UE55RU7120 device:

Installed matrix (LED panel) CY-NN055HGLV2H.
Matrix control uses the PFC Timing Controller (T-CON).
A converter combined with a power supply is used to power the backlight LEDs, and is controlled by the SO-16 Step-Down PWM controller. TO-252 switches are used as power elements of the LED driver.
The formation of the necessary supply voltages for all nodes of the SAMSUNG UE55RU7120 TV is carried out by the BN44-00932Q power module, or its analogs using PFC SO-8, PWM SO-16 microcircuits and TO-252, TO-220F power switches.

MainBoard - the main board (motherboard) is a BN41-02703A module, using CPU, eMMC, DRAM, AUDIO, DC / DC chips and others.
The BN40-00331B tuner provides reception of television programs and tuning to channels.

Instructions and updates

There are files to download for the UE55RU7120UXRU model from the manufacturer:

Latest firmware updates (latest firmwares):
File type File name Version Date Size
Update file (USB) T-MSLDEUC.zip 1371.0 10/16/2020 1284.07 Mb
Update instruction 2019_TV_Firmware_Upgrade_Instruction_T-MSLDEUC.pdf 1.0 16.06.2020 0.49 Mb
Update file (USB) T-MSLDEUC_1371.0.exe 1371.0 16.10.2020 1283.78 Mb
Update file (USB) T-MSLDEUC_1371.0_RU.exe 1371.0 10.16.2020 1283.78 Mb

User Manuals and Instructions:
File type File name Version Date Size
User manual BN68-09495D-00_URU7100H_EN_L02_190215.1.pdf 00 03/13/2019 0.86 Mb
Brief instructions BN68-09510A-00_QSG_URU7100H_CIS_190208.0.pdf 00 03/13/2019 0.45 Mb
Instruction PDF MUSDVBEUR-3.0.5_EM_MUSE_EU_ENG_201026.0.pdf 3.0.0 29.11.2020 22.13 Mb
PDF instruction MUSDVBEUR-3.0.5_EM_MUSE_EU_RUS_201026.0.pdf 3.0.0 11/29/2020 22.11 Mb

Files can be downloaded on the manufacturer's website for the UE55RU7120UXRU model


SAMSUNG UE55RU7120U TV with LCD CY-NN055HGLV2H, diagonal size 54.6 "(139 cm) 16: 9 format. The display technology of this model is implemented with LED backlighting.
CY-NN055HGLV2H sensor and MainBoard BN41-02703A software are capable of realizing images in the highest UHD quality at 3840x2160 resolution in 4K UHD, HDR standard. Image processing is performed using modern High Dynamic Range (HDR) technology with an extended range of brightness gradations.
The UE55RU7120U TV is equipped with SMART software, built-in applications and the ability to work on the Internet. The connection to the network can be carried out via Wi-Fi wireless connection. Supported media file formats: MP3, WMA, MPEG4, HEVC (H.265), MKV, JPEG.
Speaker sound system power 20 W (2x10 W) is provided by two speakers. The NICAM stereo audio processing system and the Sound Surround function are used.
Communication with other devices via an external interface is supported by standard input and output connectors: antenna input (RF), AV, component, HDMI x3, USB x2, Ethernet (RJ-45), Bluetooth, Wi-Fi, Miracast. The digital tuner is capable of receiving television channels in the DVB-T, DVB-T2, DVB-C, DVB-S, DVB-S2 standards.

The power consumed when operating from the mains is 145 W. BN44-00932Q power supply.

Dimensions: with stand 1239x793x261 mm, without stand 1239x714x59 mm.

TV weight: with stand: 17.7 kg, without stand: 17.3 kg.

Attention! Panel CY-NN055HGLV2H of SAMSUNG UE55RU7120U LED TV is an expensive and unreliable element.
Do not allow any impact on the glass and pressure on the screen surface to avoid damage to the LED panel!
It is also unsafe for liquid to spill onto the screen. Sometimes one drop is enough if it drips down the glass onto the cables to make the TV unrepairable. (SO YOU'RE BETTER, WITH YOUR COLA, FAR AWAY FROM YOUR GARBAGE TV !!)